The Language Of Dentistry | Local Anaesthetics

The Language Of Dentistry | Local Anaesthetics

One of the things that many people most dislike about dentistry is having a local anaesthetic- the medication delivered by injection that numbs the part of the mouth that is about to receive treatment. Even though the benefits of having this available are very welcome (that is, we don’t have to experience having dentistry performed on non-anaesthetised teeth), there’s still something about the process- about having a needle- that causes most people’s heart rate to increase, even if just a little bit.

If you’ve had more than one dentist taking care of you during your lifetime, you’ve probably noticed that there are a lot of different words they use to describe an injection of local anaesthetic. Similarly, people who are not dentists themselves will use a variety of words to describe the process from their point of view.

We trawled the internet looking to see whether there was already a glossary of terms describing local anaesthetic injections. Finding none, we thought it would be interesting to create our own!

But first we’ll explain a what a local anaesthetic injection actually is:

Local Anaesthetic Injections

The correct term for the type of anaesthesia that is obtained via direct injection is a “Local Anaesthetic” (as opposed to a General Anaesthetic, which renders a person completely unconscious). In dentistry, the needle tip is guided through the tissues of the mouth to a location where the nerves that provide sensation to the area to be worked upon are located. By placing the dose of local anaesthetic drug in this location, all the tissues innervated by those nerves become anaesthetised or numbed.

Dentists target the nerves that provide sensation rather than those that provide movement to the area. It might feel difficult to move your mouth after an injection, but that’s because of the numb sensation- you do actually retain the ability to move.

For Further Information

We provide some end notes to this article, under the list of words used to describe a local anaesthetic. Some of these notes will describe the process of giving a local anaesthetic injection in more detail. If you’d rather not know the details, it might be best to avoid reading those notes!

Words That Might Be Used To Describe A Dental Local Anaesthetic Injection

By brand name or drug name

There are several different local anaesthetic drugs used in dentistry in Australia, and many more different brand names.


By Abbreviation

  1. LA
  2. Local

Dental Jargon Related To The Type Of Injection Given

The type of injection

  • An infiltration
  • A block
  • Palatal
  • Mandibular block

The length of the needle tip:

  • A short (used for an infiltration or palatal injection)
  • A long (used for a mandibular block)

Or they may refer to the location of the tooth being treated:

  • Upper
  • Lower


  • Let’s just get you nice and numb first
  • (For kids) Sleepy juice
  • (For kids) Sleepy medicine
  • Let’s get started
  • Just a little pinch now
  • Just a little mossie bite

Phrases More Commonly Used By Non-Dentists

  • A shot
  • A jab
  • Deaden it
  • Freeze it
  • A needle

Unspoken Communications Between Members Of The Dental Team

Does it sometimes seem that your dentist and dental assistant are communicating telepathically? Some dental teams have worked together for long enough that the assistant will be able to anticipate the dentist’s every request. This means that it only takes a nod, a lift of the eyebrow or the tiniest hand signal for the dental assistant to know that it’s time to administer the local anaesthetic.

Delivering The Local Anaesthetic Injection

In a future article, we’ll explore the process of giving a local anaesthetic injection from the dentist’s point of view, and what tricks they have up their sleeve to make the procedure as comfortable as possible.

Notes About The Items On This List:

Brand names and drug names

In Australia, there are guidelines around using drug names in advertising, including on websites, which is why we haven’t listed any names in this article.


In dental school, dentists learn a lot of jargon and often adopt a shorthand method of communicating between themselves and other members of the dental team.

So dentists will often abbreviate the term “Local Anaesthetic” to its initials, ‘L.A’ or will just use the term ‘Local”.

Dental Jargon Related To The Type Of Injection Given

You might have noticed this yourself if you’ve had a few dental procedures done: if you are having work done on the lower jaw towards the back of your mouth it often feels like a large portion of your face has been numbed: half of the lower lip, the chin and the tongue become profoundly numb. On the other hand, if you are having an upper back tooth worked on, the injection seems to numb far less- sometimes it’s quite difficult to discern the numbed area.

This is because of the anatomy of the jaw- where the nerves that innervate the teeth are located and what other parts of the mouth they supply.

The type of injection that is used to numb an upper tooth or a lower front tooth is called an “Infiltration”: the local anaesthetic medication is delivered on the outside of the jawbone, near where the tips of the roots are located. The anaesthetic seeps through the bone and reaches the nerves encased inside. Because the local anaesthetic solution reaches the nerves near their end-point, the feeling of numbness is really centred onto the tooth that’s being worked on a tooth or two either side.

The type of injection used to numb a lower molar is called a “Mandibular Block”. The bone of the mandible is very thick, and an infiltration won’t usually work because the local anaesthetic can’t penetrate the bone and get to the nerves before they enter the roots of the teeth. In this case, the local anaesthetic needs to be delivered to a location further back, just before the location where the main trunk of the nerve enters the mandible or lower jaw.

From this point, the nerve trunk feeds all of the teeth on that side of the jaw, half the lower lip and half the chin. So when the anaesthetic is delivered, everything goes numb!

The dentist needs to use a longer needle tip to reach this location. They won’t usually ask for a ‘long’ because this might make the patient feel a little nervous (long needle? long time to give the injection? long acting? yikes!), but they may ask for a ‘short’, which sounds a lot better!


Most dentists are the masters of euphemisms- using pleasant words to describe something that people might find unpleasant or scary. There are probably hundreds of euphemisms used in Australia- this might be an interesting list to develop further!

Non-dental terms

Since dentists prefer euphemisms, they are less likely to use these types of terms, particularly ‘a shot’ or ‘a jab’, as these sound aggressive, and deaden just doesn’t sound at all pleasant.

Our research tells us that the term ‘freeze it’ is commonly used in Canada: this one is a little gentler, so your dentist may well use this term.

Dentists usually won’t even use the term “A needle’, because so many people have a fear of the needle.

What Did We Miss?

There are no doubt other words and phrases that deserve a place on this list, and we will keep adding to it as they come to mind. If you can think of anything, please let a member of the Corinna Dental team know and we’ll add it to the list.